1. Field of the Invention
The present invention relates to an improvement of an electromagnetic fuel injection valve comprising: a valve housing which includes: a valve seat member having a valve hole at a front end thereof, and a valve seat member leading to an inner end of the valve hole; a magnetic cylinder connected to a rear end of the valve seat member; and a stationary core connected to a rear end of the magnetic cylinder via a nonmagnetic collar; a valve element housed in the valve seat member so as to open and close the valve hole in cooperation with the valve seat; a movable core housed in the magnetic cylinder, the movable core being connected to the valve element and facing a front end of the stationary core; a coil housing fittingly fixed to an outer periphery of the magnetic cylinder, and housing a coil assembly provided in an outer periphery of the stationary core.
2. Description of the Related Art
Such an electromagnetic fuel injection valve is already known from, for example, Japanese Patent Application Laid-open No. 2006-2636.
In the conventional electromagnetic fuel injection valve, a coil housing, a stationary core, a movable core, and a magnetic cylinder form a magnetic path through which a magnetic flux generating an attraction force between the stationary core and the movable core passes, when electricity is supplied to a coil assembly. Also, in the conventional electromagnetic fuel injection valve, a press-fitting process is used to fittingly fix the coil housing to the magnetic cylinder. In this press-fitting process, an imbalanced distortion is generated in the magnetic cylinder due to center deviance between the magnetic cylinder and the coil housing at the time of press-fitting operation, and the distortion may propagate to the valve seat member. The propagation of distortion to the valve seat member inhibits the valve element from opening accurately, and brings the fuel injection characteristics in disorder. In the press-fitting structure between the magnetic cylinder and the coil housing, a small-diameter part is required to be formed on an outer peripheral surface of a rear end of the magnetic cylinder in order to facilitate initial fitting of the coil housing, resulting in that a gap is generated after the press fitting between the small-diameter part of the magnetic cylinder and the coil housing. This gap provides resistance in the magnetic path to some degree.